Vacuum distillation method



Dec. 16, 1941. v c. v. LrrToN vAcuuu DIISTILLATION METHOD Fild July 31,- 1939 INVENTOR Char/es K [if/arr ATTORNEY- Patented Dec. 16, 1941 VACUUM DISTI LLATI ON METHOD Charles V. Litton, Redwood City, Calif assignor of one-fourth to Jesse L. Markel and one-fourth to Alexander M. Poniatofi, both of San Francisco, Calif.

Application July 31, 1939, Serial No. 287,525

2 Claims. (01. got-52) i This invention relates generally to high vacuum distillation apparatus and processes, such as are useful for the fractional distillation of a wide variety of materials. By high vacuum I have reference to vacuums of the order of '10- mm. of mercury, or higher.

It is an object of the invention to provide a process of the above character which will be relatively simple in construction and operation, and which will make possible the separation of fractions having a high degree of purity.

Another object of the invention is to make possible progressive fractionation and reflux action in connection with distillation at high vacuums.

Additional objects of the invention will appear from the following description in which the preferredembodiment 'of the invention has been set forth 1h detail in conjunction with the accompanying drawing.

Referring to the drawing Fig. 1 is a side elevational view in cross section, illustrating diagrammatically apparatus incorporating the present invention.

Fig. 2 is a side elevational view, partly in cross section, illustrating a plurality of units somewhat as illustrated in Fig. 1, connected together to form a continuously operating series.

Fig. 3 is aside elevational view, in cross section, showing a modification of Fig. 1.

Referring first to Fig. 1 of the drawing, I have illustrated apparatus comprising the fractionating column I0, having a connection II to a'vacuum pump or other form of evacuating equipment capable of maintaining a high vacuum."

Communicating with the lower end of the fractionating column there'is a vessel I2 adapted to contain a charge of material I3, and which under normal conditions receives heat from a suitable source during the distillation cycle. An inlet pipe I4 is indicated for introducing material into the vessel I2.

The fractionating column-Ill includes the se- I ries of fractionating cups I6. These cups can be in the form of rings as illustrated, and they are formed so that when 'fllled with a condensed fraction, the fraction can overflow the inner lip into the next lower cup. The uppermost fractionating cup I6 is shown provided with a pipe connection II, whereby the lightest fraction collected in this cup can be withdrawn.

The throat or passage I8 which connects the vessel I2 withthe interior of the fractionating column III, is preferably provided with means to ously receiving'molecules of the vaporized ma- I into the fractionating column. This means is preferably in the form of a downturned lip I9, surrounding the passage I8. The space surrounding the region of lip I9 can form an additional fractionating cup 2 I, as illustrated. A tube- 22 can be provided to draw off the liquidaccumulating in cup 2|, which in a typical instance represents material from which light ends have been removed, and which does not contain waxes, color components, and miscellaneous contaminants that are caused to remain in the vessel I2. Above the throat I8 the fractionating column I0 is provided with a substantially unobstructed passage 23, for free movement of molecules of the vaporized material leaving the charge of material undergoing treatment.

.Use of the apparatus described above, and the carrying out of the present process, can be described as follows: A charge of the material undergoing treatment, which can be termed a mother liquid, is. introduced into the vessel I2. The vacuum pump connected with tube II is placed in operation, whereby the interior of the apparatus is subjected to a high vacuum of the order of say 10* mm. of mercury. The charge I3 is maintained at a suitable temperatureconsistent with the character of the fraction or fractions to be removed by applying heat to the same. Assuming maintenance of proper vacuum and temperature conditions, and also assuming that the exterior of the fractionating column I0 is suitably insulated,as by means of heat insulating material or an evacuated space, various frac- The distillation cycle is now'in .normal operation with the lower fractionating cups continuterial from the space 23. Some re-vaporization occurs continuously from the lower condensed fractions, and this re-vaporized material is condensed in upper fractionating cups. At the same time some overflow occurs from each cup and the overflow liquid passes into the next lower fractionating cup. This progressive fractionating prevent a washing up of any of the mother liquor and reflux action makes for utmost purity of the separated fractions, particularly with respect to the lightest fraction removed from the uppermost fractionating cup.

The lip l9 serves the useful purpose of preventing contamination of the condensed fractions with mother liquid. Without this lip there is a tendency for the mother liquid to be washed upwardly to intermingle with the collected fractions. However with this lip such mother liquid is returned back to the charge It.

The degree of vacuum maintained and the mean free path of movement of the molecules is of the order of the distance between the surface of the liquid undergoing treatment, and an intermediate point about midway between the ends of the fractionating column.

Fig. 3 illustrates an arrangement for providing an evacuated heat insulating jacket about the fractionating column. Thus in this instance the wall of the column are surrounded by a sealed jacket which is in direct communication with the upper end of the column. Pipe H connects to the jacket and the lightest fraction can be withdrawn from pipel'ia, instead of from the top cup of the column. Also liquid can be withdrawn from the cup 2! through pipe 22, as for example where one desires a liquid from which the light ends have been removed; and which does not contain waxes, color components and miscellaneous contaminants remaining in i2.

Fig. 2 represents a plurality of units similar to that shown in Fig. 1, connected in series. Pipe 26 in this instance represents introduction of the material undergoing treatment into an intermediate one of the fractionating rings ofthe first unit A. The lowervessel I! of the unit A is shown connected tothe drain pipe 21, which in turn leads to an intermediate one of the fractionating cups of thesecond unit B. Pipes 28 and 29 are shown for removing the light fractions from the uppermost cups of units A-and B. Material from the lower end of unit B can be drained through the pipe 30.

In operating the apparatus of Fig. 2 the material undergoing treatment can be continuously bled into unit A through pipe 26, and material.

can be continuously drained from vessel I! of unit A, into the'unit B, throughpipe 21. The material in the lower vessel I 2 of unit 3 can be maintained at a slightly higher temperature than the temperature of material in the vessel II of accep s unit A. It will be apparent that with such continuous operation the collected material in the receiver I: of unit A will maintain constant characteristics, thus making possible continual or continuous removal of-a light fraction through pipe 28. The same is also true of the material in the vessel I: of unit B, assuming of course that the volume of material in this receiver is maintained constant by -continual drainage through pipe 30.

With reference tom. 2, one of the units illustrated can be operatedcontinuously in place of batch operation as described for Figs. 1 and 3. For such operation it is desirable to introduce the liquid into an intermediate fractionating cup as indicated by lines 26 or 21 and to continually drain liquid from the lower vessel ii to maintain a substantially constant liquidlevel.

The apparatus and process described above is capable of producing fractions of extreme purity. It can be used in connection with the distillation treatment or refining of a wide variety of products, including various mineral-oils or petroleum products, and vegetable or animal oils. It can also be used to advantage to remove fractions such as vitamins 'or vitamin-like substances, from materials'such as vegetable or animal oils.

I claim:

1. In high vacuum distillation. processes, wherein a mass of material is subjected to a high vacuum-at a temperature such that one or more fractions vaporize from the mass, the steps of affording a substantially unobstructed path extending from the surface of the mass for free movement-of molecules of the vaporized fractions, continuouslycollecting a plurality of condensed fractions at regions spaceddiiferent distances from the surface of the mass and adjacent said path, and causing refluxing of the collected fractions.

2.. In high vacuum distillation processes, wherein a mass of material 'is'subjected to a high vacuum' at a temperature such that one or more fractions vaporize from the mass. the steps of affording a substantially unobstructed path, extending upwardly from the surface of the mass for free movement of molecules of the vaporized fraction, continuously collecting a plurality of condensed fractions at regions spaced at different vertical distances from the surface of the mass, whereby the higher collected fractions are progressively lighter, and causing a refluxing of the collected fractions by continuously refluxing a collected fraction into the body of collected material immediately below the same.

CHARLES V. LITION. 

